第70页 - 江苏版启东中学作业本八年级数学（上下册）

B

C

D

$6x^2y$

$2(x^2-9)$

$10a^2b^2c$

$2a^2$

5bc

$ab^2$

$\frac{x+1}{x^2-1}$

$\frac{x-1}{x²-1}$

$ \frac{1}{x²-1}$

$ \begin{aligned}解：\frac{2}{xy}&=\frac{4}{2xy} \\ \frac{x}{2y}&=\frac{x^2}{2xy} \\ \end{aligned}$

$ \begin{aligned} 解：\frac{5}{-4ab^2}&=-\frac{25a}{20a^2b^2} \\ \frac{4}{5a^2b}&=\frac{16b}{20a^2b^2} \\ \end{aligned}$

$ $

$ \begin{aligned} 解：\frac{x}{a(x-y)}&=\frac{bx}{ab(x-y)} \\ \frac{y}{b(y-x)}&= -\frac{ay}{ab(x-y)} \\ \end{aligned}$

$ \begin{aligned}解：\frac{a}{(x-y)^2}&= \frac{a(x+y)}{(x-y)^2(x+y)} \\ \frac{b}{(x-y)(x+y)}&=\frac{b(x-y)}{(x-y)^2(x+y)} \\ \end{aligned}$